In another incident highlighting the poor customer service of United Airlines, singer-songwriter and model Dua Lipa said that the crew onboard her flight refused to accommodate her request when she informed them about her sister's deadly allergy to nuts.

Lipa took to Twitter on Wednesday to state that when the crew was told about her sister's allergy, the steward responded by saying that United was not a "nut free airline", and suggested that she take medicines to deal with the allergy.

I can’t believe i’m on a @united flight rn and I told the steward that my sister was severly allergic to nuts and his reply was “we’re not a nut free airline so if she has an epi pen she might have to use that as we can’t not serve other passengers in your section nuts”

When a fan asked Lipa if the crew had announced to other passengers in the cabin about her sister's "severe" allergy, Lipa said, "They didnt! They just said well we won't serve you two nuts, but that's all we can do."

Representational image. Reuters

United Airlines' Twitter team, however, promptly responded to Lipa with a generic apology and asked for her confirmation number. "We apologise for this situation, and would like to find out more. Can you DM with your confirmation number, please?" the tweet said.

However, this is not the first time a customer has complained about United Airlines' service. In May last year, an Indian-origin man in the United States said that the airline cancelled his flight for filming a dispute involving an employee of the company. The California resident said that he ultimately re-booked his flight on a different airline, adding that he wanted United to pay for that trip.

But another incident that happened a month before this had kept the airline in news for weeks. In April 2017, a passenger was violently dragged off an overbooked United Airlines flight after he refused to be deplaned.

Videos showed authorities violently dragging him from his seat, injuring his face, throwing him on the floor and dragging him along the aisle by his arms, while his glasses slid down his face and his shirt rode up his chest. The doctor, who had identified himself as Chinese, returned to the aircraft with his face bleeding. He collapsed and was taken away on a stretcher, reports said.